I think that's part of what antoniseb is saying. If you have someone (anyone) conducting mining operations off earth then you will need to provide their equipment...eventually, presuming that off-earth mining becomes big business, the manufacturing of the equipment will be shifted off earth for the very reason you say. It's costly to get stuff up there from here.

Obviously not something that's going to happen straight away, and equally obviously there's a balance of costs to think of...is it more cost effective to launch the manufactured goods up there than it is to launch the factory (plus any support required)?